bluetooth in-situ meat thermometer, has +275 degree C range!

Anyone who wants to cook meat to 275C (527F) should re-think their recipe.

As secrets go, the idea that the active electronics will be embedded in the meat, and thus not get hotter than 100 degrees Celcius isn't all that well-concealed.

The downside is that if you get careless or absent minded and over-cook the meat until it has dried out, you've also over-cooked the thermometer.

My oven thermometer has thin leads that survive having the cooker door closed on them, and was a whole lot cheaper. And I haven't over-cooked it yet.

I had a boneless prime rib cooked sous vide at 133*F just before Christmas. A quick broil at high temp to sear the outside, and it was very good. 5 of us ate 4 lb with no leftovers!

Mikek

There is a bit of safety margin. In addition to the lag near 100 C, as moisture evaporates, the electronics can certainly handle much higher temperatures. If they're smart, they'll turn the thing off. It should be able to survive 175 to 200C.

Even a cheap tough joint of beef will slow cook fine to fall off the bone using the low hundreds C for a few hours...

But what sort of battery will survive such temperatures?

John

My guess: There is no battery. They use a capacitor and charge it inside the woodblock.

Olaf

They could also use a thermopile, though it won't.

NT

Borehole (oil well drilling) batteries: However, these only go to 200C, which is probably acceptable since they don't need to work higher than the internal temperature of the steak.

If you run the Meater instructional video, the inventor emphasizes the "ambient temperature" end of the probe, as marked by an indentation around the probe. The video at 2:46 shows temperatures of: internal 114c target 135C ambient 211C I would guess(tm) that the BT radio is in the internal region and that something inside the device requires a temperature differential in order to function.

A Peltier (Seebeck) effect thermopile could produce the necessary power using the available 80C differential temperature, but I couldn't think of a way to fit one into the probe or keep the cost within reason.

It's probably not a supercap, which typically works to 70C with a few types claiming 85C.

Oops. The video and non-existent spec sheet does not show the units of measure. Apparently, the video is in Farenheit, not Celcius. The above should be: The video at 2:46 shows temperatures of: internal 114F (45.5C) target 135F (57.2C) ambient 211F (99.4C)

The rest of my speculation is just plain wrong and should be (mostly) ignored.

But that would require a temperature difference for hot and cold junctions...

Mike.

which obviously it has. Did you think the inside of your roast joint gets to over 200C? It would be dry & burnt if it did.

NT

That's the outside end (ambient) so I guess it is just possible to get near that with a decent oven. Still quite impressive that they protected the electronics from that high a temperature at one end, especially the energy source (battery?)

I tend to roast at 180C - would be interested in looking at one for real...

How do you know how they implemented it, if you haven't taken it apart yet?

They could make the probe a solid metal rod, and attach the PCB to the outside end. The board would be cooled by conduction into the DUR, the Device Under Roasting.

Read up a bit more - I wonder how well it works in a combi microwave cooker, given the shielding necessary for microwaves is effective in the same frequency band as bluetooth?

n app on

one for

but then what will you be measuring?

If microwave heating was active, the BT receiver would almost certainly be destroyed - and probably the transmitter as well.

The shielding would as you suggest make it difficult to communicate even if the microwave heating was off.

The attenuation of the oven shielding is probably in the region of 60-70dB, so it would probably just about work if the phone or other BT device is close to the oven.

John